ATLANTA -- R.A. Dickey bid adieu to Atlanta fans with an impressive effort and the Braves used a two-run fourth inning to beat Tanner Roark and the Nationals, who saw their bid for the National League's best record weakened in Thursday night's 3-2 loss at SunTrust Park.

The Nationals now sit 4 1/2 games behind the Dodgers in the battle to earn home-field advantage throughout the NL postseason. They were baffled by Dickey, who retired 20 of the first 22 batters faced and ended up allowing just two runs over eight innings.

Roark delivered seven solid innings, but a two-run fourth fueled by Matt Wieters' throwing error proved to be the difference.

"Facing these guys back to back, as they are already a good-hitting team, is a challenge within itself," Roark said. "You can't divert from the game plan as they already know what you did last time. You gotta trust it and still do and go with the game plan. Got to execute pitches."

Roark fans Camargo

WSH@ATL: Roark strikes out Camargo swinging

Tanner Roark strikes out Johan Camargo swinging for the third out in the bottom of the 6th inning

With the victory, the Braves avoided a three-game sweep and matched last year's win total (68).

Ryan Zimmerman led off the second inning with a homer, but the Nationals had to wait until the eighth to score again off Dickey, who had allowed at least five runs in each of his past three starts. The Braves' knuckleballer worked with an early lead when Ender Inciarte began the first with a triple and scored on Ozzie Albies' RBI single -- the first of his three hits.

Dickey tosses eight innings

WSH@ATL: Dickey strikes out four over eight innings

R.A. Dickey strikes out four across eight strong innings, allowing two runs on four hits in his win vs. the Nationals

Wieters trimmed the deficit with an RBI single in the eighth inning, but Dickey escaped the jam by getting Wilmer Difo to line out to left field.

"You got to give the nod to Dickey tonight as he was good," Nationals manager Dusty Baker said.

Wieters' RBI single

WSH@ATL: Wieters smacks RBI single to left field

Matt Wieters grounds an RBI single through the hole in left to cut the Nationals' deficit in half in the top of the 8th inning

A night after blowing an eighth-inning lead by issuing three consecutive bases-loaded walks and recording a strike with just three of his 15 pitches, Arodys Vizcaino bounced back to strike out the side in the ninth for his 12th save.

"It helps when you can pitch with a lead, but I must say I'm really proud of Viz," Dickey said. "It's a real sign of a pro when you can go through a little bit of adversity and bounce back like he did."

Vizcaino nails down 12th save

WSH@ATL: Vizcaino K's the side, locks down 12th save

Arodys Vizcaino strikes out the side in dominant fashion to record his 12th save of the season in the 3-2 victory over the Nationals

MOMENTS THAT MATTEREDZimmerman's shot: Zimmerman set a career high with his 34th home run of the season in the second inning. The solo shot tied the game at 1 and went a Statcast-projected 424 feet. More >

Zimmerman's 34th home run

ATL@WSH: Zimmerman cranks 34th HR to set career high

Ryan Zimmerman launches a solo home run to deep right field to tie the game at 1 in the 2nd, his 34th of the season to set a career high

Decisive fourth: After Albies opened the fourth with a single and advanced to third base when Wieters' pickoff attempt sailed into right field, Freddie Freeman followed with a sacrifice fly. Nick Markakis then doubled and scored on Johan Camargo's decisive two-out single.

"Roark pitches," Braves manager Brian Snitker said. "He's fun to watch. He changes speeds and knows where the ball is going. He's been tough on us over the long haul. So, it was good to get some runs."

Camargo's RBI single

WSH@ATL: Camargo knocks RBI single up the middle

Johan Camargo cracks an RBI single to center field to double the Braves' lead to 3-1 in the bottom of the 4th inning

QUOTABLE
"You're always playing for something. You might think you're out of the race because you're this many games back, but you're always being evaluated. You've got pride to play and be competitive. If you go out there and you don't have that mindset, [the game] will eat you alive." -- Dickey, who notched his 120th win in what was his final home start of the season and possibly of his career

SOUND SMART WITH YOUR FRIENDS
Zimmerman's 34 home runs rank as the fifth most in a single season since the franchise moved to Washington. He is the active leader with 113 career RBIs against the Braves.

EIGHTH-INNING DELAY
There was an eight-minute delay as the Nationals attempted to make six different changes to their lineup before the bottom of the eighth. Difo ended the top half with a pinch-hit lineout while batting in the ninth spot. But the plan to have Difo remain in the game to play shortstop in place of Trea Turner was negated when Sammy Solis entered from the bullpen and stepped on the mound before the lineup changes were relayed to home-plate umpire Nic Lentz. As soon as Solis stepped on the rubber, he had to bat in the ninth spot. This led to the confusion that forced Baker to make a slew of adjustments to make his lineup right. More >

Lineup card confusion in Atlanta

WSH@ATL: Errant lineup card causes delay in action

Dusty Baker attempts to make a double switch for the bottom of the 8th inning, but there's confusion with the lineup card causing a delay

WHAT'S NEXTNationals: Washington opens a three-game set against the Mets at 7:10 p.m. ET on Friday at Citi Field. Edwin Jackson will start the series opener and hopes to rebound from allowing 16 earned runs in his last three starts.

Braves:Sean Newcomb will take the mound when Atlanta opens a three-game series against Philadelphia at 7:35 p.m. ET on Friday. Newcomb has produced a 3.86 ERA over his past nine starts. This will mark the start of the final series at SunTrust Park during its inaugural season.